A known truck signaling system comprises a combination turn signal/hazard warning signal switch that can be selectively operated by the driver (operator) of the vehicle to signal a right turn, to signal a left turn, or to signal a hazard warning. A common flasher is used to flash the appropriate lamps of the truck for each of the three respective signals, and it is connected in a feed to a hazard warning input terminal of the combination turn signal/hazard warning signal switch. The combination turn signal/hazard warning signal switch also has a brake (stop) input terminal to which a feed from a normally open brake (stop) switch is connected. Brake application that is concurrent with non-actuation of the combination turn signal/hazard warning signal switch will cause the rear brake (stop) lamps on both right and left sides of the vehicle to illuminate while front signal lamps that signal turn and/or hazard warning remain off. Actuation of the turn signal/hazard warning signal switch to signal a turn, concurrent with brake application, will cause the rear brake (stop) lamp(s) on the side of the vehicle toward the signaled direction of turning to flash intermittently while those rear lamp(s) toward the opposite side remain continuously illuminated. Actuation of the combination turn signal/hazard warning signal switch to signal a hazard warning will, in the absence of brake application, cause the rear brake (stop) lamp(s) toward both sides of the vehicle, and other lamps that signal hazard warning, to flash intermittently; however, should the brakes be concurrently applied, the rear brake lamps on both sides will continuously illuminate as well as the remaining lamps, because the closed brake switch shorts out the flasher.
A known system ECM for a truck comprises two inputs for determining if the brakes are being applied by the driver. One input is sometimes referred to as "brake normally open" input, and the other, as "brake normally closed" input. These two inputs are intended to receive respective binary logic level signals, which are supplied from a D.C. voltage source (typically the vehicle electrical power supply) via a normally open switch and via a normally closed switch respectively. When the brakes are not being applied, the "brake normally open" input receives no voltage (corresponding to low logic level), while the "brake normally closed" input receives live D.C. voltage (corresponding to high logic level). When the brakes are being applied, the "brake normally open" input receives live D.C. voltage, while the "brake normally closed" input receives no voltage.
A truck engine, such as in a heavy truck, may have what is known as an "idle shut-down" system. Such an "idle shut-down" system is effective to automatically shut down the engine if the brakes are not applied, the accelerator pedal is not depressed, and/or the transmission is not in gear for a predetermined amount of time, five minutes for example. Integration of an idle shut-down system with the aforementioned system ECM in a vehicle having the aforementioned turn signal/hazard warning system must assure that there is no undesired interaction between these systems, and it is toward this objective that the present invention is directed.
One aspect of the present invention relates to a new and unique circuit for interfacing a brake switch and a combination turn signal/hazard warning signal switch with a system electronic control module, particularly where an associated system, such as an idle shut-down system, obtains a brake signal input from the circuit, so that no undesired electrical interactions, like spurious feedback paths for example, occur. A presently preferred embodiment of the invention employs known system components but connects them in a new and unique cooperative association to achieve the desired objective.
The foregoing, along with further features and advantages of the invention, will be seen in the following disclosure of a presently preferred embodiment of the invention depicting the best mode contemplated at this time for carrying out the invention. The disclosure includes drawings, as now briefly described.